[528993] Complete I18N of org.eclipse.eef.properties.ui plug-in Add missing strings and fix the Messages class initialization. Bug: 528993 Change-Id: I653a39ddf2b1d60d2ecabb89548b2b9da7eca101 Cherry-Picks: 525990 Signed-off-by: Pierre-Charles David <pierre-charles.david@obeo.fr>